JP5084802B2 - Lithium ion secondary battery - Google Patents

Description

  The present invention relates to a lithium ion secondary battery.

As a power source for electronic equipment, a lithium ion secondary battery is expected as a secondary battery expected to be reduced in size and weight. As the positive electrode active material of these lithium ion secondary batteries, metal oxides containing Li such as lithium cobaltate (LiCoO ₂ ) and lithium manganate (LiMn ₂ O ₄ ) have been studied and put into practical use.

  However, in recent years, as the demand for reducing the cost of batteries has increased, there has been a demand for the development of technology for extending the life using inexpensive materials.

Therefore, as a positive electrode material, lithium manganate (LiMn ₂ O) has the characteristics that it is abundant in resources, is inexpensive, and is thermally stable even during abuse such as overcharge. ₄ ) is attracting attention.

  However, lithium manganate has a problem in terms of life characteristics due to problems such as elution of Mn due to HF and the like present in the electrolytic solution, resulting in a decrease in capacity and an increase in resistance accompanying the charge / discharge cycle. .

  In order to improve the charge / discharge characteristics of lithium manganate, various studies have been made so far.

  In Patent Document 1 and Patent Document 2, a method of mixing a layered lithium Mn oxide with lithium manganate is proposed.

  That is, in Patent Document 1, in a lithium secondary battery mainly composed of a lithium manganese complex oxide as a positive electrode active material, the lithium manganese complex oxide includes two or more lithium manganese complex oxides having different crystal structures, And the lithium secondary battery whose reversible capacity of the said positive electrode is below the reversible capacity of a negative electrode is disclosed. According to this lithium secondary battery, it is described that the burden on the negative electrode during charging can be reduced and the deterioration of the negative electrode can be suppressed.

Further, Patent Document 2 discloses an electrode group in which a positive electrode sheet and a negative electrode sheet are formed via a separator and a non-aqueous electrolyte, a laminated outer case that houses the electrode group, the positive electrode sheet, and the negative electrode In a non-aqueous secondary battery having a positive electrode lead and a negative electrode lead connected to each of the sheets, the positive electrode active material used for the positive electrode formed on the positive electrode sheet is spinel lithium manganese oxide and layered lithium A non-aqueous secondary solution containing manganese oxide and having a lithium compound (except LiBF ₄ ) containing boron in a non-aqueous solution in which a lithium salt is dissolved in a carbonate-based non-aqueous solvent. A battery is disclosed. It is described that this non-aqueous secondary battery can increase the output maintenance rate in pulse charge / discharge by adding a lithium compound containing boron.

  Patent Document 3 discloses a nonaqueous electrolytic solution containing unsaturated sultone. It is described that by using this non-aqueous electrolyte, gas generation and self-discharge can be suppressed during high-temperature storage of the non-aqueous electrolyte secondary battery.

  Patent Document 4 includes a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte using a lithium-containing composite oxide having a layered structure as an active material, and the potential of the positive electrode when fully charged is 4.35 V or more on the basis of Li. A nonaqueous electrolyte secondary battery, wherein the nonaqueous electrolyte contains vinylethylene carbonate or a derivative thereof and a predetermined cyclic sulfate derivative or a predetermined cyclic sulfonate derivative. Is disclosed.

  Patent Document 5 discloses a non-aqueous electrolyte comprising a positive electrode using a positive electrode active material made of a lithium-containing metal composite oxide having a layered structure, a negative electrode, and a non-aqueous electrolyte in which an electrolyte is dissolved in a non-aqueous solvent. In the secondary battery, a positive electrode active material in which nickel is contained in the metal excluding lithium in the lithium-containing metal composite oxide in an amount of 50 mol% or more is used, and the non-aqueous electrolyte includes the unsaturated bond in the ring. A non-aqueous electrolyte secondary battery is disclosed in which a sulfur-containing cyclic compound having a content of 0.1 to 5% by weight is added.

In Patent Document 6, in a non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, the non-aqueous electrolyte contains at least one kind of unsaturated sultone represented by a predetermined chemical formula, and the positive electrode contains the non-aqueous electrolyte. The positive electrode active material is a composite oxide Li _x Mn _a Ni _b Co _c O _d having a layered α-NaFeO ₂ type crystal structure (0 <x <1.3, a + b + c = 1, 1.7 ≦ d ≦ 2. 3) A non-aqueous electrolyte secondary battery in which | a−b | <0.03 and 0.33 ≦ c <1 is disclosed.

  Patent Document 7 is a nonaqueous electrolyte secondary battery that includes a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte, and the potential of the positive electrode after charging is 4.35 V or more on a Li basis, A lithium-containing composite oxide having a layered structure containing manganese as a constituent element or a lithium-containing composite oxide having a spinel structure containing manganese as a constituent element as an active material, and the non-aqueous electrolyte includes a predetermined cyclic sulfate derivative Alternatively, a non-aqueous electrolyte secondary battery containing a predetermined cyclic sulfonate derivative is disclosed.

  Patent Document 8 discloses a positive electrode active material for a non-aqueous electrolyte secondary battery having a lithium transition metal composite oxide having at least a layered structure and a spinel structure, wherein the lithium transition metal composite oxide is obtained by an X-ray diffraction method. A positive electrode active material for a non-aqueous electrolyte secondary battery having two or more independent peaks between 2θ = 18.4 and 19.6 ° is disclosed.

JP 2003-36846 A JP 2007-165111 A JP 2002-329528 A JP 2009-104838 A JP 2008-235146 A JP 2007-207723 A JP 2006-344390 A JP 2007-128714 A

  An object of the present invention is to suppress an increase in resistance in a cycle having a wide charge / discharge range of a lithium ion secondary battery using a positive electrode material in which a layered lithium Mn oxide is mixed with lithium manganate.

  The lithium ion secondary battery of the present invention is a lithium ion secondary battery including a positive electrode active material containing spinel manganese and a layered lithium manganese oxide, a negative electrode active material, and an electrolyte solution, wherein the electrolyte solution is vinylene. It contains carbonate and unsaturated sultone.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the lithium ion secondary battery which the resistance rise in a charging / discharging cycle is suppressed and is long life.

It is a schematic cross section which shows the lithium ion secondary battery of this invention. It is a graph which shows the evaluation result of the capacity | capacitance maintenance factor in the lithium ion secondary battery of the Example by this invention. It is a graph which shows the evaluation result of the resistance increase rate in the lithium ion secondary battery of the Example by this invention. It is a graph which shows the evaluation result of the capacity | capacitance maintenance factor of the positive electrode active material in the lithium ion secondary battery of the Example by this invention. It is a graph which shows the evaluation result of the resistance increase rate of the positive electrode active material in the lithium ion secondary battery of the Example by this invention.

  The present invention relates to an electrolyte solution additive for a lithium ion secondary battery having excellent life characteristics.

  The present invention mixes and further uses layered lithium Mn oxide (layered lithium manganese oxide) in order to apply inexpensive and highly heat-stable lithium manganate as a positive electrode active material of a lithium ion secondary battery. VC (vinylene carbonate) and unsaturated sultone are added to and mixed with the electrolytic solution. Thereby, the capacity | capacitance fall and resistance rise in a charging / discharging cycle can be suppressed, and the lifetime improvement as a lithium ion secondary battery is realizable.

  FIG. 1 is a schematic cross-sectional view of a lithium ion secondary battery.

  A lithium ion secondary battery (also referred to as a lithium secondary battery) has a configuration in which a separator 3 is interposed between a positive electrode plate 1 and a negative electrode plate 2. These positive electrode plate 1, negative electrode plate 2 and separator 3 are wound and sealed together with a non-aqueous electrolyte in a battery can 4 made of stainless steel or aluminum.

  A positive electrode lead piece 7 is connected to the positive electrode plate 1, and a negative electrode lead piece 5 is connected to the negative electrode plate 2, so that a current is taken out. Insulating plates 9 are provided between the positive electrode plate 1 and the negative electrode lead piece 5 and between the negative electrode plate 2 and the positive electrode lead piece 7, respectively. Further, between the battery can 4 that is in contact with the negative electrode lead piece 5 and the sealing lid portion 6 that is in contact with the positive electrode lead piece 7, leakage of the electrolyte is prevented, and a positive electrode and a negative electrode are provided. A packing 8 is provided.

  The positive electrode plate 1 is obtained by applying a positive electrode mixture to a current collector made of aluminum or the like. The positive electrode mixture includes a positive electrode active material, a conductive material, a binder, and the like that contribute to occlusion and release of lithium.

  The negative electrode plate 2 is obtained by applying a negative electrode mixture to a current collector formed of copper or the like. The negative electrode mixture includes a negative electrode active material, a conductive material, a binder, and the like that contribute to occlusion and release of lithium.

  As the negative electrode active material, metallic lithium, a carbon material, or a material capable of inserting lithium or forming a lithium compound can be used, and a carbon material is particularly preferable.

  Examples of the carbon material include graphite such as natural graphite and artificial graphite, and amorphous carbon such as coal-based coke, coal-based pitch carbide, petroleum-based coke, petroleum-based pitch carbide, and pitch-coke carbide. Preferably, the above carbon material is subjected to various surface treatments.

  These carbon materials can be used not only in one kind but also in combination of two or more kinds. Examples of the material capable of inserting lithium or forming a compound include metals such as aluminum, tin, silicon, indium, gallium, and magnesium, alloys containing these elements, and metal oxides containing tin, silicon, and the like. . Furthermore, the composite material of the above-mentioned metal, an alloy, a metal oxide, and the carbon material of a graphite type or an amorphous carbon is mentioned.

  As one of the active materials (positive electrode active material) of the positive electrode plate 1, lithium manganate having a spinel structure (hereinafter sometimes abbreviated as “spinel manganese”) is used.

As this spinel manganese, specifically, the general formula Li _a Mn _b M _c O ₄ (where a + b + c = 3, 1.0 ≦ a ≦ 1.1, 0 <c ≦ 0.07. M is And at least one selected from the group consisting of Ni, Fe, Zn, Mg and Cu).

The spinel manganese has LiMn ₂ O ₄ as a base material and is intended to suppress deterioration due to M substitution. The sum a + b + c of the contents of Li, Mn and M is preferably a + b + c = 3 in order to maintain the spinel structure of LiMn ₂ O ₄ which is the base material. When a + b + c ≠ 3, the spinel structure is disturbed.

  The Li content a is 1.0 ≦ a ≦ 1.1, but when a <1.0, the Li site is occupied by other elements, so that the diffusion of Li ions is inhibited. In the case of 1.1 <a, the content of transition metals such as Mn in the positive electrode active material is relatively decreased with respect to the content of Li, and the capacity of the lithium ion secondary battery is decreased. End up. A more preferable range is 1.06 ≦ a ≦ 1.1.

  The content c of M (at least one selected from the group consisting of Ni, Fe, Zn, Mg and Cu) is 0 <c ≦ 0.07, but when c = 0, the average valence of Mn is 3 Since the crystal structure becomes unstable because of less than .5, a large amount of manganese is eluted in the electrolytic solution by charge and discharge, thereby promoting deterioration. On the other hand, in the case of 0.07 <c, since M is substituted with bivalent, the valence of Mn is greatly increased in order to maintain electrical neutrality. Since charge / discharge of spinel manganese is performed by changing the valence of Mn, the capacity of the lithium ion secondary battery decreases when the valence of Mn increases. A more preferable range is 0.01 ≦ c ≦ 0.03.

As another type of active material of the positive electrode plate _1, using _{Li (Co x Ni y Mn z} ) O 2 (x + y + z = 1). Hereinafter, this active material is also referred to as a layered lithium manganese oxide.

  An example of a method for manufacturing a lithium ion secondary battery is as follows.

  A positive electrode active material is mixed with a conductive material of carbon material powder and a binder such as polyvinylidene fluoride to prepare a slurry. The mixing ratio of the conductive material to the positive electrode active material is preferably 3 to 10% by weight. The mixing ratio of the binder to the positive electrode active material is preferably 2 to 10% by weight. At this time, the mixing ratio of the lithium manganate and the layered lithium Mn oxide is preferably about 90:10 to 50:50 by weight. And in order to disperse | distribute a positive electrode active material uniformly in a slurry, it is preferable to fully knead | mix using a kneader.

  The obtained slurry is coated on both sides of an aluminum foil having a thickness of 15 to 25 μm by, for example, a roll transfer machine. After coating on both sides, the electrode plate of the positive electrode plate 1 is formed by press drying. As for the thickness of the mixture part which mixed the positive electrode active material, the electrically conductive material, and the binder, 200-250 micrometers is desirable.

  The negative electrode is mixed with a binder and applied in the same manner as the positive electrode, and press dried to form an electrode. Here, the thickness of the negative electrode mixture is preferably 100 to 150 μm. For the negative electrode plate 2, a copper foil having a thickness of 7 to 20 μm is used as a current collector. The mixing ratio of the material to be applied is preferably about 90:10 to 98: 2 by weight ratio of the negative electrode active material and the binder.

  The obtained electrode plate is cut to a predetermined length to form an electrode, and the tab portion of the current drawing portion is formed by spot welding or ultrasonic welding. The tab portion is made of a metal foil made of the same material as the current collector having a rectangular shape, and is installed to take out current from the electrode, and becomes the positive electrode lead 7 and the negative electrode lead 5.

  A microporous film, for example, a separator 3 formed of polyethylene (PE), polypropylene (PP) or the like is sandwiched between the tabbed positive electrode plate 1 and the negative electrode plate 2, and this is rolled into a cylindrical shape to form an electrode. A group is housed in a battery can 4 which is a cylindrical container. Alternatively, a bag-shaped separator may be used to store the electrodes therein, which are sequentially stacked and stored in the square container. The material of the container is preferably stainless steel or aluminum.

  After the battery group is stored in the battery can 4, a non-aqueous electrolyte is injected and sealed using the lid 6 and the packing 8.

Non-aqueous electrolytes include ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), methyl acetate (MA), and methyl propyl carbonate (MPC). In a solvent such as vinylene carbonate (VC), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), lithium bis-oxalatoborate (LiBOB) and the like as an electrolyte It is desirable to use a solution in which a lithium salt is dissolved. The concentration of the electrolyte is preferably 0.7 to 1.5M.

  Thus, the manufactured lithium ion secondary battery has a configuration in which a pair of positive and negative electrodes face each other with a separator and a non-aqueous electrolyte therebetween, and has a high energy density and excellent high rate characteristics. A secondary battery can be provided.

  Examples of the present invention are shown below. It goes without saying that the present invention is not limited to these examples.

  An example of a method for manufacturing the lithium ion secondary battery in this example is as follows.

  The production of an 18650 (diameter 18 mm × height 650 mm) type battery will be described.

  First, a positive electrode active material, a carbon material powder conductive material, and a PVdF binder were mixed at a weight ratio of 90: 4.5: 5.5, and an appropriate amount of NMP was added to prepare a slurry. . As the positive electrode active material at this time, a mixture of lithium manganate (spinel manganese) and layered lithium Mn oxide at an equal weight ratio was used. The prepared slurry was stirred for 3 hours with a planetary mixer and kneaded.

Next, the kneaded slurry was applied to both sides of an aluminum foil having a thickness of 20 μm using an applicator of a roll transfer machine. This was pressed with a roll press machine so that the mixture density was 2.65 g / cm ³ to obtain a positive electrode.

  Amorphous carbon is used as the negative electrode active material, carbon black is used as the conductive material, PVdF is used as the binder, and the mixture is mixed at a weight ratio of 92.2: 1.6: 6.2. The mixture was stirred for a few minutes and kneaded.

  The kneaded slurry was applied on both sides of a 10 μm thick copper foil using an applicator, dried, and then pressed with a roll press to obtain a negative electrode.

  The positive electrode and the negative electrode were each cut into a predetermined size, and a current collecting tab was installed by ultrasonic welding on a portion of these electrodes where the slurry was not applied (uncoated portion).

  A porous polyethylene film was sandwiched between the positive electrode and the negative electrode, wound into a cylindrical shape, and then inserted into a 18650 type battery can.

  After connecting the current collector tab and the lid of the battery can, the lid of the battery can and the battery can were welded by laser welding to seal the battery.

  Finally, a nonaqueous electrolyte was injected from a liquid injection port provided in the battery can to obtain an 18650 type battery. The battery weight was 38 g.

As an electrolytic solution, 1.0 mol of LiPF ₆ was dissolved in a mixed solvent of EC (ethylene carbonate) and EMC (ethyl methyl carbonate), and VC (vinylene carbonate) and 1,3-Prop which are unsaturated sultone were dissolved therein. -1-ene Sultone (chemical formula: C ₃ H ₄ O ₃ S) was added in an amount of 1 wt% with respect to the total electrolyte solution after mixing.

  Hereinafter, the cycle characteristic evaluation of the battery will be described.

  The produced battery was transferred to a constant temperature bath at 25 ° C. and held for 1 hour. In the initial charge / discharge, the battery was charged at a constant current / constant voltage up to 4.2 V at a current of 0.3 A, and then discharged to 2.7 V at a current of 0.3 A. Then, after charging at a constant current / constant voltage up to 4.2 V with a current of 1 A, discharging up to 2.7 V with a current of 1 A was repeated 3 cycles. The discharge capacity at the third cycle was evaluated as the initial discharge capacity of the present invention.

  Thereafter, the battery was transferred into a thermostat kept at 45 ° C., charged at a constant current of up to 4.2 V with a current of 0.5 A, and then discharged up to 3 V with a current of 0.5 A was repeated 200 cycles. After the end of 200 cycles, the battery was transferred into a constant temperature bath maintained at 25 ° C. and held for 3 hours until the battery temperature reached 25 ° C. Thereafter, the battery was charged at a constant current / constant voltage up to 4.2 V at a current of 1 A, and discharge up to 2.7 V at a current of 1 A was repeated three cycles, and the discharge capacity at the third cycle was evaluated as the capacity after the cycle. And it moved in a 45 degreeC thermostat, and continued the 0.5 A charging / discharging cycle. The cycle evaluation was performed until the cumulative number of cycles reached 1000 cycles.

VC (vinylene carbonate) and 1,3-Prop-1-ene Sultone (chemical formula: C ₃ H ₄ O ₃ S) that are unsaturated sultone and 1. The process was performed under the same conditions as in Example 1 except that an amount of 5 wt% was added.

VC (vinylene carbonate) and 1,3-Prop-1-ene Sultone (chemical formula: C ₃ H ₄ O ₃ S), which are unsaturated sultone, are added to the electrolyte solution in an amount of 0. Except that the amount of 5 wt% was added, it was performed under the same conditions as in Example 1 (Comparative Example 1).
This was performed under the same conditions as in Example 1 except that VC (vinylene carbonate) was added to the electrolytic solution in an amount of 1.0 wt% with respect to the total electrolytic solution.

(Comparative Example 2)
The same procedure as in Example 1 was performed except that the positive electrode active material was lithium manganate (spinel manganese) alone.

"Method for evaluating DC resistance"
A method for evaluating the resistance of a 18650 battery manufactured and evaluated according to the present invention will be described below. As resistance, DC resistance was measured from the slope of the current-voltage plot.

  After evaluating the initial capacity as described in Example 1, the battery was charged at a constant current / constant voltage up to 4.2 V at a current of 0.5 A. After a pause of 30 minutes, discharge was performed for 11 seconds at a current of 0.5 A. In addition, after a 30-minute pause, discharge was performed for 11 seconds at a current of 1 A, and after a pause of 30 minutes, a discharge was performed for 11 seconds at a current of 2 A.

  Then, the difference from the open circuit voltage (OCV) immediately before the discharge is performed at each current (0.5A, 1A, 2A) is obtained, the current value evaluated on the horizontal axis, and the voltage difference (OCV-10) on the vertical axis. (Second voltage) was plotted, a DC resistance value was calculated from the slope, and this value was taken as the initial resistance.

  And after the capacity | capacitance confirmation test for every 200 cycles, DC resistance was evaluated in the same procedure, and the change from an initial value was defined as a resistance increase rate.

"Evaluation results of capacity maintenance rate"
The evaluation results of Examples 1 to 3 and Comparative Example 1 are shown in FIG.

From this figure, the batteries of Examples 1 to _{3 in} which VC (vinylene carbonate) and 1,3-Prop-1-ene Sultone (chemical formula: C ₃ H ₄ O ₃ S), which are unsaturated sultones, were added to the electrolytic solution. It can be seen that a decrease in capacity is suppressed as compared with Comparative Example 1 in which only VC is added. And in the battery of Examples 1-3, it turns out that a capacity | capacitance fall is suppressed, so that there are much addition amounts of VC and unsaturated sultone.

"Evaluation results of resistance increase rate"
The evaluation results of Examples 1 to 3 and Comparative Example 1 are shown in FIG.

From this figure, the batteries of Examples 1 to _{3 in} which VC (vinylene carbonate) and 1,3-Prop-1-ene Sultone (chemical formula: C ₃ H ₄ O ₃ S), which are unsaturated sultones, were added to the electrolytic solution. It can be seen that the resistance increase is suppressed as compared with Comparative Example 1 in which only VC is added. And in the battery of Examples 1-3, it turns out that the resistance rise is suppressed most in Example 1 whose addition amount of VC and unsaturated sultone is 1 wt%, respectively.

  Here, the operation when VC and unsaturated sultone are applied to the battery electrolyte will be described.

  VC thinks that the double bond existing in the molecule is cleaved by an electrochemical action and is positively (positively) charged and adsorbed on the surface of the negative electrode to form a protective film.

  Unsaturated sultone has a bond of sulfur (S) and oxygen (O) in its molecule and is polarized, but the terminal oxygen is negatively (negatively) charged. It is considered that a protective film is formed by adsorbing on the surface.

  It is considered that the increase in resistance is suppressed by these actions.

  In Comparative Example 1, since only the VC is contained in the electrolytic solution and no unsaturated sultone is contained, the positive electrode is not sufficiently protected, and the resistance is considered to be higher than those in Examples 1 to 3.

“Evaluation results of capacity retention rate of cathode active material”
The evaluation results of Example 1 and Comparative Example 2 are shown in FIG.

From this figure, when the positive electrode active material is lithium manganate (spinel manganese) alone, VC (vinylene carbonate) and unsaturated sultone, 1,3-Prop-1-ene Sultone (chemical formula: C ₃ ) are used as the electrolyte. It can be seen that even when H ₄ O ₃ S) is added, the capacity is greatly reduced at the 200th cycle from the initial stage. Therefore, it has been confirmed that the effect of the present invention is clearer when the positive electrode active material is a mixture of lithium manganate (spinel manganese) and layered lithium Mn oxide.

"Evaluation results of resistance increase of positive electrode active material"
The evaluation results of Example 1 and Comparative Example 2 are shown in FIG.

From this figure, similarly to the evaluation result of the capacity retention rate, when the positive electrode active material is lithium manganate (spinel manganese) alone, 1, 3-Prop which is VC (vinylene carbonate) and unsaturated sultone in the electrolytic solution. It can be seen that even when -1-ene Sultone (chemical formula: C ₃ H ₄ O ₃ S) is added, the resistance increase at the 200th cycle from the initial stage is large. Therefore, it has been confirmed that the effect of the present invention is clearer when the positive electrode active material is a mixture of lithium manganate (spinel manganese) and layered lithium Mn oxide.

  According to the present invention, when a material obtained by mixing lithium manganate (spinel manganese) with a layered lithium Mn oxide is used as a positive electrode material of a lithium ion secondary battery, VC (vinylene carbonate) and unsaturated are used as an electrolyte. By simultaneously adding sultone, a decrease in capacity and an increase in resistance are suppressed, and a lithium ion secondary battery that is thermally stable even at the time of abuse and inexpensive can be provided.

Since the positive electrode active material obtained in the present invention is thermally stable as compared with lithium cobalt oxide (LiCoO ₂ ) that has been used conventionally, a large-sized lithium ion secondary battery excellent in safety is required. It can be expected to be applied to power sources for mobiles and stationary power storage.

  1: positive electrode plate, 2: negative electrode plate, 3: separator, 4: battery can, 5: negative electrode lead piece, 6: sealing lid, 7: positive electrode lead piece, 8: packing, 9: insulating plate.

Claims (3)

  In a lithium ion secondary battery including a positive electrode active material including spinel manganese and a layered lithium manganese oxide, a negative electrode active material, and an electrolytic solution, the electrolytic solution includes vinylene carbonate and unsaturated sultone. Lithium ion secondary battery. The layered-type lithium manganese _{oxide, Li (Co x Ni y Mn} z) O 2 ( where a x + y + z = 1. ) The lithium ion secondary battery of claim 1, wherein the a. The spinel manganese is Li _a Mn _{b McO 4} (where a + b + c = 3, and M is at least one element selected from the group consisting of Ni, Fe, Zn, Mg, and Cu). The lithium ion secondary battery according to claim 1, wherein the lithium ion secondary battery is provided.

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